[Commotion-dev] Serval Mesh Helper Device / ISM long-range meshing work

[Dan Staples]

Paul, that is very interesting! I am particularly interested in what
kind of throughput you can get on that frequency. Do you attach an
external antenna to one of the RP-SMA connectors?

As for battery power, I've been experimenting with providing power to a
Raspberry Pi using a series of D-cell batteries. D-cells have the most
energy capacity per density/size than any other common consumer battery,
from my investigation. For the RPi, which uses 5V USB power, drawing
500-1000 mA, a couple alkaline D-cells could last 2-3 days. I bet this
could work for your Mesh Helper as well. All I needed to get that
working was a simple step-down DC-DC converter, which costs US$2 max. A
handful of D-cells aren't exactly pocket-sized, but certainly something
you could stash in a backpack. I'm about to buy a high-current solar
cell as well, to try to make an always-on solar-powered device.

Let us know of your progress!

Dan

On 02/07/2013 09:46 AM, Ben West wrote:
> Likewise, Ubiquiti also sells 900MHz versions of their Nanostation and
> Bullet access points.  I understanding these units essentially just
> have 2.4/5.8GHz chipsets that have been translated to a different
> band, and with some consequent penalty in spectral efficiency.
>
> E.g.
> http://www.wirelessnetworkproducts.com/locom900.aspx
>
> I would like to assume OpenWRT and derivatives will run w/o complaint
> on such 900MHz units, but I'm guessing it's not that simple.
>
> On Wed, Feb 6, 2013 at 11:00 PM, Paul Gardner-Stephen
> <paul at servalproject.org <mailto:paul at servalproject.org>> wrote:
>
>     Hi All,
>
>     Just a heads up on some stuff we are doing at Serval that I think will
>     be of interest to Commotion deployments more generally.
>
>     We are now actively working on what we call our "Mesh Helper Device",
>     the prototype of which will consist of a TP-LINK WR703N running
>     Commotion OpenWRT + servald, connected to an RFD900 ISM 915MHz band
>     packet radio and a rechargeable battery.
>
>     This gives the potential for much greater range than just WiFi, as
>     well as offering some resistance for 2.4GHz jamming in places where
>     that is a problem.
>
>     The RFD900s with current firmware in urban settings offer 5x to 10x
>     range compared with WiFi.  For example, I could receive a decent
>     signal with one radio sitting on my lounge, and the other radio with
>     me walking around the block, up to about 150m away -- with the signal
>     path obliquely through perhaps 8 or 10 houses, fences, cats, dogs,
>     trees and everything else.
>
>     With good clear line of sight, and a low noise floor, ranges of 10km
>     or more are possible, with some evidence pointing to the actual limit
>     being around 80km - 120km in very ideal conditions.
>
>     We have already managed to get Serval Mesh traffic, including some
>     Rhizome transfers (but not yet voice) running over one of these links:
>
>     servalpaul.blogspot.com.au/2013/02/breaking-wifi-barrier-serval-mesh.html
>     <http://servalpaul.blogspot.com.au/2013/02/breaking-wifi-barrier-serval-mesh.html>
>
>     We think a complete Mesh Helper Device, including these really nice
>     radios could be built and sell for <US$200.  It may also be possible
>     to use a cheaper compatible (but slightly lower performance) radio and
>     get the price down to <US$100.
>
>     The RFD900 firmware only does point-to-point communications, but it is
>     entirely possible to make it do "ad-hoc" point-to-multipoint
>     communications.  Perhaps this is something for us to look at as a
>     follow on after our current work block is complete.
>
>     We are hoping to have a couple of these with us in New Zealand in a
>     couple of weeks for the KiwiEx field trial. General outline of our
>     thinking for KiwiEx at present is at:
>
>     http://developer.servalproject.org/dokuwiki/doku.php?id=content:exercises:kiwiex2013
>
>     If there are other things people would like tested while we are there,
>     let me know, and we will endeavour to cover them.
>
>     Paul.
>
>     _______________________________________________
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>     Commotion-dev at lists.chambana.net
>     <mailto:Commotion-dev at lists.chambana.net>
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>
>
>
>
> -- 
> Ben West
> http://gowasabi.net
> ben at gowasabi.net <mailto:ben at gowasabi.net>
> 314-246-9434
>
>
> _______________________________________________
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-- 
Dan Staples

Open Technology Institute
https://commotionwireless.net

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